Method for the Encoding and Decoding of a Sequence of Words, Corresponding Signal, Encoder, Decoder, Computer Programs and Storage Means

1. A method for encoding a sequence of source words, the method comprising: a step of selecting an encoding function to be applied to a source word to be encoded as a function of the content of the word to be encoded and of at least one preceding source word in the sequence so that the concatenation of two consecutive encoded words has no isolated binary element-between two binary elements with a value different from that of the isolated binary element; and a step of encoding the word to be encoded implementing the selected encoding function.

2. A method according to claim 1 , wherein said step of encoding the word to be encoded produces an encoded word with a fixed length as a function of the length of the word to be encoded.

3. A method according to claim 1 ,wherein said step of selecting an encoding function takes account of the binary element of a last encoded word, a first binary element of the result of the application of the encoding function to the source sequence to be encoded being equal to the binary element of the last encoded word.

4. A method according to claim 3 , further comprising a step of storing the last binary element of the last encoded word.

5. A method according to claim 1 , further comprising a step of computing a difference between a number of binary elements associated with a first binary value and a number of binary elements associated with a second binary value, the binary elements belonging to a set of previously encoded words, said step of selecting an encoding function taking account of the result of the computation so as to approximately balance the number of binary elements respectively associated with the first and second binary values, and the binary elements belonging to a set of words encoded after application of the encoding function.

6. A method according to claim 5 , wherein said step of selecting an encoding function takes account of the sign of the difference.

7. A method according to claim 6 , wherein the application of the encoding function, selected during said selecting step, to the source word to be encoded: contains at least as many elements corresponding to the first binary value as elements corresponding to the said second binary value if the difference is strictly negative; and contains at most as many elements corresponding to the first binary value as elements corresponding to the second binary value if the difference is strictly positive.

8. A method according to claim 1 , wherein said step of selecting an encoding function comprises selecting an encoding function from among: a first predetermined encoding function having a result that is an encoded sequence with a mean weight greater than or equal to half the number of elements of the encoded word, and having a first element that has a first binary value representing 0; a second predetermined encoding function having a result that is an encoded word with a weight lower than or equal to the mean weight, and having a first element that possesses a first binary value representing 0; a third predetermined encoding function having a result that is an encoded word with a weight greater than or equal to the mean weight, and having a first element that has a first binary value representing 1; and a fourth predetermined encoding function having a result that is an encoded word with a weight lower than or equal to the mean weight, and having a first element that has a first binary value representing 1.

9. A method according to claim 8 , wherein the first and second encoding functions coincide when each of the first and second encoding functions produces encoded words with a weight equal to the mean weight; and wherein the third and fourth functions coincide when each of the third and fourth functions produces encoded words with a weight equal to the mean weight.

10. A method according to claim 8 , further comprising: a step of storing a first encoding table associated with the first encoding function and a second encoding table associated with the second encoding function; and a step of reading an encoded sequence in one of the encoding tables associated with the selected encoding function if one of the first or second encoding functions is selected.

11. A method according to claim 1 , wherein at least one of the encoding functions comprises a step of determining a binary complement of the word to be encoded.

12. A method for decoding a sequence of binary encoded words, wherein the sequence does not possess an isolated binary element between two binary elements having a value different from that of the isolated binary element, and wherein the decoding method comprises: a step of decoding each of the binary encoded words, the binary encoded words being decoded separately, and, for each of the binary encoded words: a step of reading a decoded word in a decoding table at a location that is a function of the encoded word; and a step of verifying the validity of the decoded word as a function of the result of said reading step.

13. A method according to claim 12 , wherein all of the binary encoded words have the same determined length.

14. A method according to claim 12 , further comprising, for each of the binary encoded words, a step of verifying the validity of the received word as a function of the words of the sequence, previously received.

15. A method according to claim 12 , further comprising, for each of the binary encoded words, a step of selecting a decoding function to be applied to the binary encoded word as a function of content of the encoded word.

16. A method according to claim 15 , wherein said selecting step comprises a sub-step of extracting a sub-word of the binary encoded word.

17. A method according to claim 16 , further comprising: a sub-step of determining the weight of the encoded binary word; and wherein said sub-step of extracting the sub-sequence comprises determining the positions of the binary elements extracted from the binary encoded word as a function of the weight.

18. A method according to claim 17 , further comprising: a step of computing a linear combination of the binary elements of the sub-word; and a step of reading a decoding table as a function of the linear combination.

19. A method according to claim 12 , further comprising, for each of the binary encoded words: a step of identifying the first binary element of the binary encoded word; and a step of computing the binary complement of the binary encoded word if the first binary element corresponds to a predetermined value.

20. A method according to claim 12 , further comprising, for each of the binary encoded words, a step of checking the validity of the encoded word as a function of the weight of the encoded word.

21. A device for encoding a sequence of source words, the device comprising: a device configured to select an encoding function to be applied to a source word to be encoded as a function of the content of the word to be encoded and of at least one preceding source word in the sequence so that the concatenation of two consecutive encoded words has no isolated binary element between two binary elements that have a value different from that of the isolated binary element; and a device configured to encode the word to be encoded implementing the selected encoding function.

22. A device for decoding a sequence of binary encoded words, wherein the sequence does not possess an isolated binary element between two binary elements that have a value different from that of the isolated binary element and wherein the device comprises: a decoder adapted to decode each of the binary encoded words, the binary encoded words being decoded separately, and, for each of the binary encoded words: a reader adapted to read a decoded word in a decoding table at a location that is a function of the encoded word; and a validator adapted to verify the validity of the decoded word as a function of the result of said reader.

23. A computer program product adapted to the encoding of a sequence of source words, said computer program product comprising program code instructions recorded on a readable medium that can be used in a computer comprising: programming means readable by computer to perform a step of selecting an encoding function to be applied to a source word to be encoded as a function of the content of the word to be encoded and of at least one preceding source word in the sequence so that the concatenation of two consecutive encoded words has no isolated binary element between two binary elements with a value different from that of the isolated binary element, and programming means readable by computer to perform a step of encoding the word to be encoded implementing the selected encoding function.

24. A computer program product adapted to the decoding of a sequence of binary encoded words, said sequence possessing no isolated binary element between two binary elements having a value different from that of the isolated binary element, said computer program product comprising program code instructions recorded on a readable medium that can be used in a computer comprising: programming means readable by computer to perform: a step of decoding each of the binary encoded words, the binary encoded words being decoded separately, and, for each of the binary encoded words: a step of reading a decoded word in a decoding table at a location that is a function of the encoded word; and a step of verifying the validity of the decoded word as a function of the result of the reading step.

25. A computer readable storage medium, which is totally or partially removable, storing a set of machine executable instructions, said instructions being executable by a computer adapted to the encoding of a sequence of source words to perform: a step of selecting an encoding function to be applied to a source word to be encoded as a function of the content of the word to be encoded and of at least one preceding source word in the sequence so that the concatenation of two consecutive encoded words has no isolated binary element between two binary elements with a value different from that of the isolated binary element, and a step of encoding the word to be encoded implementing the selected encoding function.

26. A computer readable storage medium, which is totally or partially removable, storing a set of machine executable instructions, said instructions being executable by a computer adapted to the decoding of a sequence of binary encoded words, the sequence possessing no isolated binary element between two binary elements having a value different from that of the isolated binary element, to perform: a step of decoding each of the binary encoded words, the binary encoded words being decoded separately, and, for each of the binary encoded words: a step of reading a decoded word in a decoding table at a location that is a function of the encoded word; and a step of verifying the validity of the decoded word as a function of the result of the reading step.